26 results found
Krauspe P, Tsokkou D, Causa M, et al., 2018, Terahertz short-range mobilities in neat and intermixed regions of polymer: fullerene blends with controlled phase morphology, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 6, Pages: 22301-22309, ISSN: 2050-7488
Causa M, De Jonghe-Risse J, Scarongella M, et al., 2016, The fate of electron–hole pairs in polymer:fullerene blends for organic photovoltaics, Nature Communications, Vol: 7, ISSN: 2041-1723
There has been long-standing debate on how free charges are generated in donor:acceptor blends that are used in organic solar cells, and which are generally comprised of a complex phase morphology, where intermixed and neat phases of the donor and acceptor material co-exist. Here we resolve this question, basing our conclusions on Stark effect spectroscopy data obtained in the absence and presence of externally applied electric fields. Reconciling opposing views found in literature, we unambiguously demonstrate that the fate of photogenerated electron–hole pairs—whether they will dissociate to free charges or geminately recombine—is determined at ultrafast times, despite the fact that their actual spatial separation can be much slower. Our insights are important to further develop rational approaches towards material design and processing of organic solar cells, assisting to realize their purported promise as lead-free, third-generation energy technology that can reach efficiencies over 10%.
Buchaca-Domingo E, Vandewal K, Fei Z, et al., 2015, Direct correlation of charge transfer absorption with molecular donor: acceptor interfacial area via photothermal deflection spectroscopy, Journal of the American Chemical Society, Vol: 137, Pages: 5256-5259, ISSN: 0002-7863
Here we show that the charge transfer (CT) absorption signal in bulk-heterojunction solar cell blends, measured by photothermal deflection spectroscopy, is directly proportional to the density of molecular donor:acceptor interfaces. Since the optical transitions from the ground state to the interfacial CT state are weakly allowed at photon energies below the optical gap of both the donor and acceptor, we can exploit the use of this sensitive linear absorption spectroscopy for such quantification. Moreover, we determine the absolute molar extinction coefficient of the CT transition for an archetypical polymer:fullerene interface. The latter is ∼100 times lower than the extinction coefficient of the donor chromophore involved, allowing us to experimentally estimate the transition dipole moment as 0.3 D and the electronic coupling between the ground and CT states to be on the order of 30 meV.
Scarongella M, De Jonghe-Risse J, Buchaca-Domingo E, et al., 2015, A Close Look at Charge Generation in Polymer:Fullerene Blends with Microstructure Control, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 137, Pages: 2908-2918, ISSN: 0002-7863
De Jonghe-Risse J, Causa M, Buchaca-Domingo E, et al., 2015, Using the Stark effect to understand charge generation in organic solar cells, 14th Conference on Physical Chemistry of Interfaces and Nanomaterials, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Dou F, Buchaca-Domingo E, Sakowicz M, et al., 2015, The effect of phase morphology on the nature of long-lived charges in semiconductor polymer:fullerene systems, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 3, Pages: 3722-3729, ISSN: 2050-7526
Shaw J, Zhong H, Yau CP, et al., 2014, Alternating Copolymers Incorporating Dithienogemolodithiophene for Field-Effect Transistor Applications, MACROMOLECULES, Vol: 47, Pages: 8602-8610, ISSN: 0024-9297
Buchaca-Domingo E, Ferguson AJ, Jamieson FC, et al., 2014, Additive-assisted supramolecular manipulation of polymer:fullerene blend phase morphologies and its influence on photophysical processes, MATERIALS HORIZONS, Vol: 1, Pages: 270-279, ISSN: 2051-6347
Marshall J, Schroeder BC, Bronstein H, et al., 2014, Benzocarborano[2,1-b:3,4-b ']dithiophene Containing Conjugated Polymers: Synthesis, Characterization, and Optoelectronic Properties, MACROMOLECULES, Vol: 47, Pages: 89-96, ISSN: 0024-9297
Scarongella M, Paraecattil AA, Buchaca-Domingo E, et al., 2014, The influence of microstructure on charge separation dynamics in organic bulk heterojunction materials for solar cell applications, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 2, Pages: 6218-6230, ISSN: 2050-7488
Koch FPV, Rivnay J, Foster S, et al., 2013, The impact of molecular weight on microstructure and charge transport in semicrystalline polymer Semiconductors poly(3-hexylthiophene), a model study, PROGRESS IN POLYMER SCIENCE, Vol: 38, Pages: 1978-1989, ISSN: 0079-6700
Jahnke AA, Djukic B, McCormick TM, et al., 2013, Poly(3-alkyltellurophene)s are solution-processable polyheterocycles., J Am Chem Soc, Vol: 135, Pages: 951-954
The synthesis and characterization of a series of poly(3-alkyltellurophene)s are described. Polymers are prepared by both electrochemical and Kumada catalyst transfer polymerization methods. These polymers have reasonably high molecular weights (M(n) = 5.4-11.3 kDa) and can be processed in a manner analogous to that of their lighter atom analogues. All examples exhibit red-shifted optical absorption, as well as solid-state organization, as evidenced by absorption spectroscopy and atomic force microscopy. Overall, the synthesis and characterization of these materials open up a wide range of future studies involving tellurium-based polyheterocycles.
Fei Z, Gao X, Smith J, et al., 2013, Near Infrared Absorbing Soluble Poly(cyclopenta[2,1-b:3,4-b ']dithiophen-4-one)vinylene Polymers Exhibiting High Hole and Electron Mobilities in Ambient Air, CHEMISTRY OF MATERIALS, Vol: 25, Pages: 59-68, ISSN: 0897-4756
Dou F, Buchaca-Domingo E, Sakowicz M, et al., 2013, Long-lived photoexcitations in intercalated, partially and predominantly non-intercalated polymer: fullerene blends, Conference on Physical Chemistry of Interfaces and Nanomaterials XII, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Zhong H, Li Z, Buchaca-Domingo E, et al., 2013, Low band gap dithienogermolodithiophene copolymers with tunable acceptors and side-chains for organic solar cells, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 1, Pages: 14973-14981, ISSN: 2050-7488
Tsoi WC, James DT, Domingo EB, et al., 2012, Effects of a Heavy Atom on Molecular Order and Morphology in Conjugated Polymer:Fullerene Photovoltaic Blend Thin Films and Devices, ACS NANO, Vol: 6, Pages: 9646-9656, ISSN: 1936-0851
Jamieson FC, Domingo EB, McCarthy-Ward T, et al., 2012, Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells, Chemical Science, Vol: 3, Pages: 485-492, ISSN: 2041-6520
Solution processed polymer/fullerene blend films are receiving extensive attention as the photoactive layer of organic solar cells. In this paper we report a range of photophysical, electrochemical, physicochemical and structural data which provide evidence that formation of a relatively pure, molecularly ordered phase of the fullerene component, phenyl-C61-butyric acid methyl ester (PCBM), may be the key factor driving the spatial separation of photogenerated electrons and holes in many of these devices. PCBM crystallisation is shown to result in an increase in its electron affinity, providing an energetic driving force for spatial separation of electrons and holes. Based upon our observations, we propose a functional model applicable to many organic bulk heterojunction devices based upon charge generation in a finely intermixed polymer/fullerene phase followed by spatial separation of electrons and holes at the interface of this mixed phase with crystalline PCBM domains. This model has significant implications for the design of alternative acceptor materials to PCBM for organic solar cells.
Fei Z, Kim Y, Smith J, et al., 2012, Comparative Optoelectronic Study between Copolymers of Peripherally Alkylated Dithienosilole and Dithienogermole, Macromolecules
Here we report a simple methodology for the synthesis of dithienosilole and dithienogermole monomers in which the necessary solubilizing long chain alkyl groups are incorporated into the peripheral 3,5-positions of the fused ring. We report four novel monomers in which methyl or butyl groups are attached to the bridging Si and Ge atom. Copolymers with bithiophene were synthesized by a Stille polymerization in high molecular weight. We report the optical, electrical, electrochemical and morphological properties of the resulting polymers. We find that the nature of the bridging heteroatom (Si or Ge) has only a minor influence on these properties, whereas the nature of the alkyl chain attached to the bridging atom is found to have a much larger effect.
Shahid M, McCarthy-Ward T, Labram J, et al., 2012, Low band gap selenophene-diketopyrrolopyrrole polymers exhibiting high and balanced ambipolar performance in bottom-gate transistors, Chemical Science, Vol: 3, Pages: 181-185, ISSN: 2041-6520
We report the synthesis of a selenophene-diketopyrrolopyrrole monomer and its co-polymerisation with selenophene and thieno[3,2-b]thiophene monomers by Stille coupling. The resulting low band gap polymers exhibit ambipolar charge transport in organic field effect transistors. High and balanced electron and hole mobilities in excess of 0.1 cm2 V-1 s-1 were observed in bottom-gate, bottom-contact devices, suggesting that selenophene inclusion is a promising strategy for the development of ambipolar organic semiconductors.
Labram JG, Domingo EB, Stingelin N, et al., 2011, In-Situ Monitoring of the Solid-State Microstructure Evolution of Polymer:Fullerene Blend Films Using Field-Effect Transistors, Adv. Funct. Mater., Vol: 21, Pages: 356-363, ISSN: 1616-3028
Fei Z, Kim JS, Smith J, et al., 2011, A low band gap co-polymer of dithienogermole and 2,1,3-benzothiadiazole by Suzuki polycondensation and its application in transistor and photovoltaic cells, JOURNAL OF MATERIALS CHEMISTRY, Vol: 21, Pages: 16257-16263, ISSN: 0959-9428
Ball JM, Bouwer RKM, Kooistra FB, et al., 2011, Soluble fullerene derivatives: The effect of electronic structure on transistor performance and air stability, Journal of Applied Physics, Vol: 110, Pages: 014506-014506
Buchaca E, Man SP, Motevalli M, et al., 2010, N-Carbazolylmethylphosphonic acid—synthesis, metal coordination, emissive aggregate formation and spectroscopic features, New Journal of Chemistry, Vol: 34, Pages: 2592-2592, ISSN: 1144-0546
Buchaca E, Man SP, Motevalli M, et al., 2009, Carbazolylmethylphosphonate compounds – Synthesis, coordination and fluorescence in solution and cells, Polyhedron, Vol: 28, Pages: 4115-4121, ISSN: 0277-5387
Man SP, Benoit DM, Buchaca E, et al., 2006, Synthesis, Structural Characterization, Experimental, and Computational Spectrophotometric Studies of 8-Quinolinyloxymethyphosphonate Compounds, Inorganic Chemistry, Vol: 45, Pages: 5328-5337, ISSN: 0020-1669
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.